Diffusion and Perfusion: The Keys to Fat Grafting

Background: Fat grafting is now widely used in plastic surgery. Long-term graft retention can be unpredictable. Fat grafts must obtain oxygen via diffusion until neovascularization occurs, so oxygen delivery may be the overarching variable in graft retention. Methods: We studied the peer-reviewed literature to determine which aspects of a fat graft and the microenvironment surrounding a fat graft affect oxygen delivery and created 3 models relating distinct variables to oxygen delivery and graft retention. Results: Our models confirm that thin microribbons of fat maximize oxygen transport when injected into a large, compliant, well-vascularized recipient site. The “Microribbon Model” predicts that, in a typical human, fat injections larger than 0.16 cm in radius will have a region of central necrosis. Our “Fluid Accommodation Model” predicts that once grafted tissues approach a critical interstitial fluid pressure of 9 mm Hg, any additional fluid will drastically increase interstitial fluid pressure and reduce capillary perfusion and oxygen delivery. Our “External Volume Expansion Effect Model” predicts the effect of vascular changes induced by preoperative external volume expansion that allow for greater volumes of fat to be successfully grafted. Conclusions: These models confirm that initial fat grafting survival is limited by oxygen diffusion. Preoperative expansion increases oxygen diffusion capacity allowing for additional graft retention. These models provide a scientific framework for testing the current fat grafting theories

Diffusion and Perfusion: The Keys to Fat Grafting

Background: Fat grafting is now widely used in plastic surgery. Long-term graft retention can be unpredictable. Fat grafts must obtain oxygen via diffusion until neovascularization occurs, so oxygen delivery may be the overarching variable in graft retention. Methods: We studied the peer-reviewed literature to determine which aspects of a fat graft and the microenvironment surrounding a fat graft affect oxygen delivery and created 3 models relating distinct variables to oxygen delivery and graft retention. Results: Our models confirm that thin microribbons of fat maximize oxygen transport when injected into a large, compliant, well-vascularized recipient site. The “Microribbon Model” predicts that, in a typical human, fat injections larger than 0.16 cm in radius will have a region of central necrosis. Our “Fluid Accommodation Model” predicts that once grafted tissues approach a critical interstitial fluid pressure of 9 mm Hg, any additional fluid will drastically increase interstitial fluid pressure and reduce capillary perfusion and oxygen delivery. Our “External Volume Expansion Effect Model” predicts the effect of vascular changes induced by preoperative external volume expansion that allow for greater volumes of fat to be successfully grafted. Conclusions: These models confirm that initial fat grafting survival is limited by oxygen diffusion. Preoperative expansion increases oxygen diffusion capacity allowing for additional graft retention. These models provide a scientific framework for testing the current fat grafting theories

Descriptive epidemiology of 399 histologically confirmed newly diagnosed meningeal solitary fibrous tumours and haemangiopericytomas in France: 2006–2015

International audiencePurpose: Meningeal solitary fibrous tumour (SFT) and haemangiopericytoma (HPC) are uncommon tumours that have been merged into a single entity in the last 2021 WHO Classification of Tumors of the Central Nervous System. To describe the epidemiology of SFT/HPC operated in France and, to assess their incidence.Methods: We processed the French Brain Tumour Database (FBTDB) to conduct a nationwide population-based study of all histopathologically confirmed SFT/HPC between 2006 and 2015.Results: Our study included 399 SFT/HPC patients, operated in France between 2006 and 2015, in one of the 46 participating neurosurgical centres. The incidence reached 0.062, 95%CI[0.056-0.068] for 100,000 person-years. SFT accounted for 35.8% and, HPC for 64.2%. The ratio of SFT/HPC over meningioma operated during the same period was 0.013. SFT/HPC are about equally distributed in women and men (55.9% vs. 44.1%). For the whole population, mean age at surgery was 53.9 (SD ± 15.8) years. The incidence of SFT/HPC surgery increases with the age and, is maximal for the 50-55 years category. Benign SFT/HPC accounted for 65.16%, SFT/HPC of uncertain behaviour for 11.53% and malignant ones for 23.31%. The number of resection progresses as the histopathological behaviour became more aggressive. 6.7% of the patients with a benign SFT/HPC had a second surgery vs.16.6% in case of uncertain behaviour and, 28.4% for malignant SFT/HPC patients.Conclusion: Meningeal SFT and HPC are rare CNS mesenchymal tumours which both share common epidemiological characteristics, asserting their merging under a common entity. SFT/HPC incidence is less that one case for 1 billion per year and, for around 100 meningiomas-like tumours removed, one SFT/HPC may be diagnosed. SFT/HPC are equally distributed in women and men and, are mainly diagnosed around 50-55 years. The more aggressive the tumour, the higher the probability of recurrence

Descriptive epidemiology of 30,223 histopathologically confirmed meningiomas in France: 2006–2015

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